Study On In-plane Vibration Induced Tube-to-tube Impact Wear Behavior Of Heat Exchange Tubes In Nuclear Steam Generator

In the nuclear power system,the steam generator(SG)is the core device that realizes the heat conduction of the primary circuit and the secondary circuit.Because the secondary side of the steam generator is washed by the high-temperature and high-pressure two-phase flow,the U-shaped heat exchange tube bend area will be In-plane vibration occurs.When the vibration amplitude of the heat exchange tubes exceeds the gap between the heat exchange tubes,impact collisions will occur between the heat exchange tubes,causing contact damage to the heat exchange tubes,which poses a huge hidden danger to the normal operation of nuclear power.To this end,this paper carried out the inter-tube impact wear test of Inconel 690 heat exchange tubes under different conditions,aiming to explore the impact wear failure law and damage mechanism of 690 heat exchange tubes,which can provide a theory for nuclear power equipment to resist impact wear and normal operation Support,can also supplement the basic theoretical system of impact wear.In this paper,based on the existing test-bed,the impact wear test device of 690 heat exchange tube has been successfully designed by means of additional impact impact collision device and test signal acquisition system,and the impact wear test of 690 heat exchange tube in dry state at room temperature and under water environment has been carried out.The impact force applied in the test is 20 N,30N,40 N and 50 N,the impact times are 10000,50000,100000 and 200000,and the impact frequency is 30 Hz.The micro inspection of the wear scar morphology was carried out by means of optical microscope,sigma type scanning electron microscope,contour GT optical profiler and electronic energy spectrometer,and the following conclusions were obtained:(1)The impact load has an important effect on the impact wear behavior of 690 heat exchange tube.With the increase of the impact load,the wear degree of the heat exchange tube is gradually intensified,which is manifested in the increase of the mass loss,the wear mark area and the surface roughness of the heat exchange tube.When the impact load is small,there will be furrows and a large number of debris on the surface of the heat exchange tube.The main damage mechanism of the surface of the heat exchange tube is abrasive wear.When the impact load is large,the surface material of the heat exchange tube will be subject to large bending stress,and micro cracks and peeling will appear on the surface of the tube.The damage mechanism of the heat exchange tube is fatigue peeling and oxidation wear.(2)The impact times also have an important influence on the impact wear behavior of 690 heat exchange tubes.With the increase of the number of impact,the degree of wear and damage of heat exchange tube is gradually increased.In the initial stage of impact,the wear damage of heat exchange tube is relatively slight.With the increase of impact times,the impact energy absorbed by the heat exchange tube is also increasing,and the micro deformation on the tube surface is also accumulating,so the surface damage degree of the heat exchange tube is also increasing.(3)Under the same impact condition,the wear damage degree of the heat exchange tube in the water environment is smaller than that in the dry condition.The damage mechanism of heat exchange tube is fatigue peeling and oxidation wear under dry condition at room temperature,and the damage mechanism of heat exchange tube is fatigue peeling and abrasive wear under water environment at room temperature.